[Elecraft] K2, distorted audio signal

[Walter Underwood]

I was trying to get a DR11-W to talk between a rack-mounted VAX-11/750 and an Ungermann-Bass Ethernet box. I spent weeks on it and finally tracked it down to a house-built parallel cable that had a shared ground wire. We switched to a DEC cable that alternated signal and ground wires across the flat cable. Worked the first time.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jul 31, 2025, at 1:42 PM, Jack Brindle via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> I was quite surprised during my time at Sun Microsystems that the address and data buses on our Sparc Systems were not terminated. In fact there was no consideration at all given to them being transmission lines, even though they were running at a few GHz. The systems worked very well, with no problems. These days high-speed buses in computers are serial. It turns out that running a few hundred parallel lines that are the same electrical length (and thus have the same propagation timing) is a very, very difficult problem to solve. Much easier to have just a few serial lanes that carry the data at super-high speeds.
> 
> Sometimes we can overthink things when simple is what is really needed. Wayne did a really good job with the K2…
> 
> 73,
> Jack, W6FB
> 
> 
>> On Jul 31, 2025, at 2:47 PM, Fred Jensen via Elecraft <elecraft at mailman.qth.net> wrote:
>> 
>> "It is amazing how we were able to build radios with only 2 sided PCBs for 50 ohm micro or strip lines."
>> 
>> In the later 70's we took delivery of a Data General Nova 3 mini-computer that came with a FORTRAN compiler.  The circuit boards were 15" square-ish, 2-layer.  We quickly discovered that periodically but unpredictably, execution of the compiler would quit dead on a DO statement in the source.  It just stopped.  No other statement, only a DO and not all the time, but if it stopped, it did so on every recompile of that source. <mailto:elecraft at mailman.qth.net>
>> 
>> After several DG visits they finally believed us and showed up with their Guru in flip-flops, ragged board shorts, a torn T-shirt, and fairly long-ish uncombed hair.  He said almost nothing and the other 3 DG's [in "computer expert" business attire] were very attentive to him. <mailto:elecraft at mailman.qth.net>
>> 
>> He spent most of the morning with the 'scope making notes in a beat-up notebook in indecipherable script and diagrams.  Finally muttered something to his minions who raced to get him an Xacto knife, some very light insulated wire, and the soldering station.  He cut both ends of several parallel traces and replaced them with twisted pair jumpers. The compiler never stalled on a DO statement again.
>> 
>> Problem likely would never have occurred had the board had a 3rd ground layer between the two outer ones but they they had yet to be invented.
>> 
>> 73,
>> 
>> Fred ["Skip"] K6DGW
>> Sparks NV DM09dn
>> Washoe County
>> 
>> 
>> 
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